In recent years, advances in the accuracy and portability of sensing and radar systems have led to their increased use in the detection of target objects. As a result, more people now rely on the accuracy of these systems than ever. For example, the portability and accuracy of the Lightweight Counter-Mortar Radar (LCMR) system has led to its increased use in field operations. People stake their lives on the accuracy of these radar systems when used in the field. As such, testing an LCMR system for accuracy is of utmost importance.
FIG. 1 illustrates a real-world application of an LCMR system in the field. LCMR systems are used to detect and locate one or more moving objects and to calculate a prior location of the one or more moving objects. One typical application of an LCMR system is to determine the firing locations of launchers. Portable LCMR systems can be transported into the field by vehicles or parachutes, or can be disassembled and carried by one or more individuals. Once in the field, an LCMR system can quickly be assembled. In the illustration of FIG. 1, LCMR system 10 provides 360-degree surveillance by scanning with a cylindrically phased array antenna 12 mounted on a tripod 14. Antenna 12 scans the surrounding area by generating beams of radio frequency radiation 15. When an object 16 is within the field of the LCMR system, the beam of radiation is reflected off of the object and reflected beam 17 is detected by LCMR system 10. The detected object is then tracked to determine the object's trajectory. A processor (not shown) then performs a calculation based on the trajectory to determine the location of a launcher 18 that fired the object. Having determined the location of firing launcher 18, appropriate action can be taken to disable launcher 18. Nevertheless, the accuracy of the location information generated by an LCMR system is important in taking these countermeasures. As such, LCMR systems need to be thoroughly tested before use.
One traditional method for testing LCMR systems and other sensing and radar systems involves live-fire testing. With live-fire testing, a real-world field scenario is created at an outdoor range. For example, testing personnel set up a launcher in a specific location on an outdoor range, fire a shell, and determine whether the LCMR system accurately determines the firing location. This testing scenario looks just like the real-world example in FIG. 1 with the exception that, rather than being operated in the field, the LCMR is operated on a controlled outdoor testing range. However, live-fire testing is suboptimal, because it is time consuming, harmful to the environment, and expensive, both in terms of the quantity of shells that need to be fired and in the amount of testing ground resources that need to be consumed.
FIG. 2 illustrates another method for testing sensor and radar systems, called “near field scanning.” With near field scanning, an antenna probe 21 is moved to a position in a two-dimensional frame 22. The probe is moved along a vertical axis along a vertical arm 23 of the frame and a horizontal axis along a horizontal arm 24 of the frame. The probe moves around the frame to cover the whole array of the frame, similar to a raster scan. By probing the radiation from the sensor or radar system at the different locations, the near field scanner is able to characterize the beam pattern of the system. However, these near field testing systems are also suboptimal, because they only characterize the electric and magnetic fields of the antenna radiation and do not accurately test real-world applications of sensor and/or radar systems.
FIGS. 3a and 3b illustrate alternative approaches being used to test real-world applications of scanning and/or radar systems. FIG. 3a illustrates a mechanical live-fire test set (MLFTS) for testing an LCMR system. Using this approach, LCMR system 10 is taken off of its tripod stand and placed on a rotator device 31. A vertical motion rail 32 with a controllable antenna probe 33 is placed in the field of LCMR system 10. A target object can be simulated at various elevations by controllably moving antenna probe 33 vertically up and down motion rail 32. Various azimuths of the target object can be simulated by rotating LCMR system 10 with rotator device 31. In testing a simulated target object at a specific desired location, rotator device 31 rotates LCMR system 10 to a desired azimuth and motion rail 32 moves probe antenna 33 vertically to the desired elevation. LCMR system 10 then sends a beam of radio frequency radiation 34 into the field, where it is detected by antenna probe 33. Antenna probe 33 acts as a repeater and transmits a beam of radio frequency radiation 35 that is calibrated to simulate the reflected radiation off of the simulated target and back to LCMR system 10.
FIG. 3b illustrates an electronic live-fire test set (ELFTS) for testing an LCMR system 10. The ELFTS operates similarly to the MLFTS, but uses a column of antenna elements 41 rather than a single antenna probe on a motion rail. When an antenna element at a particular vertical placement along the electronic rail, location 42 for example, detects a radiation beam 43 from LCMR system 10, the antenna element at location 42 acts as a repeater and transmits a beam of radio frequency radiation 44 that is calibrated to simulate the reflected radiation off of the simulated target back to LCMR system 10.
While the MLFTS and ELFTS testing approaches are improvements over prior sensor and/or radar testing approaches, they still have significant costs and inefficiencies associated with them. For example, MLFTS and ELFTS testing is performed in an anechoic chamber in order to mitigate electronic interference from the environment. These chambers must be large to accommodate the radar structure and testing apparatus, are expensive to create, and require LCMR systems to be transported to the chamber facility. Furthermore, radar target simulation using antennas normally requires that the injection antenna be placed in the radar antenna far-field. If the target trajectories involve high elevation angles, an impractically tall injection antenna support is needed. This is especially true for high radar bands and/or large radar apertures. As a result, the motion rail of the MLFTS must be very tall in height and cannot be easily transported to different locations. The vertical column of antenna elements of the ELFTS has been modified into ruggedized, all-weather versions that can be disassembled for transport into the field. Nevertheless, these versions require a great deal of time and effort in setup, as the column of antenna elements must be assembled to great height and the LCMR system must still be placed on a rotator device in the field.
Accordingly, there is a need for a portable, efficient, and inexpensive approach for testing LCMR systems and other sensor and/or radar systems that can be used to more easily test these systems in a variety of desired locations. There is also a need for a system and method for variable geometry moving target injection that is compact and that does not compromise normal radar operation. Furthermore, there is a need to broaden the scope and application of radar testing systems and methods to more sensor and target types both inside and outside anechoic chambers.
The systems and methods of the present disclosure address one or more of the problems set forth above.